“I Can’t Drive 55” -- The Pure Power of EZGC

Restek’s on-line version of EZGC is a selectivity tool that relies on a pre-loaded library of thermodynamic retention indices. This makes it possible to predict retention times and optimize chromatographic methods without the need to analyze compound sets under many different conditions.  EZGC selects the stationary phase by simultaneously adjusting: film thickness, temperature, column length, column internal diameter and flow.  Users can enter each compound or cut/paste large lists of compounds into the program.

Since its introduction there have been thousands of searches across a broad range of compound classes. The program outputs: compound retention time, resolution and peak width along with the column conditions and dimensions. A model chromatogram is provided to illustrate retention, peak width and resolution. Users have the option to view compound mass spectral data with the added benefit of overlaying mass spectra for coeluting analytes. Specific searches can be saved and accessed at a later date and technical service is there to help every step of the way. For example if the user is interested in an alternate carrier gas or has questions about a resulting column recommendation technical service can provide modeled chromatograms for other columns and carrier gas types.

For compounds that are not in Restek’s library but are in our chromatogram database there is a recommendation and links to those chromatograms.  Methane is commonly searched and while there is not a library for this analyte we have a variety of applications and chromatograms that are linked to this search. While EZGC will accept many different names for the same compound; the most common challenge for the user to date has been mis-spellings or combinations of compounds entered. One notable example is m/p-xylene.  A search for m/p-xylene will indicate the compound is not found when in fact both m-xylene and p-xylene are both found on over a dozen libraries in Restek’s database.   Restek’s new EZGC program allows the user to instantly optimize a list of compounds and jump start method optimization.

I pulled 233 compounds (that I know are in the 624Sil library) and load them into the program and let it rip. And yes, it tests dozens of phases and dimension configurations, and provides a chromatogram, retention time, peak widths, and resolution for 233 compounds in 25 seconds. The older version could only handle 100 compounds at any given time and while it is quite powerful it did not have the ability to simultaneously evaluate different stationary phases.

 

All 233 compounds modeled for retention time, peak width and resolution

More detailed view of the middle of the chromatogram

 

Moving the cursor over the compounds will display the compound IDs

 

 

Clicking on the magnifying glass in the compound list will display the spectra of each compound -- coelutions can be displayed to easily reveal interferences. Check out our other links on this topic!

 

Related Articles:

Szopa, C., R. Sternberg, D. Coscia, H. Cottin, F. Raulin, F. Goesmann, H. Rosenbauer. Gas Chromatography for in situ analysis of a cometary nucleus: characterization of diphenyl / dimethylpolysiloxane stationary phases: J. Chrom. A. 1999. 863: 157-169

Matevz, P., J.M. Davis, C.D.Samuel. Prediction of Thermodynamic Parameters in Gas Chromatography from Molecular Structure: Hydrocarbons. J. Chem. Inf. Comput. Sci. 2004. 44: 399-409.

Samuel C., J.M. Davis. Application of statistical-overlap theory to gas chromatograms simulated on nonpolar stationary phases with commercial software: J. Chrom. A. 1999: 842: 65-77.